The present invention relates to a liquid ejection method, liquid ejecting head, a head cartridge and liquid ejecting apparatus.
More particularly, the present invention relates to a liquid ejecting method using growth of bubble and displacement of a movable member.
The present invention is applicable to a printer for printing on a recording material such as paper, thread, fiber, textile, leather, metal, plastic resin material, glass, wood, ceramic or the like; a copying machine; a facsimile machine including a communication system; a word processor or the like including a printer portion; or another industrial recording device comprising various processing devices.
In this specification, xe2x80x9crecordingxe2x80x9d means not only forming an image of letter, figure or the like having specific meanings, but also includes forming an image of a pattern not having a specific meaning.
An ink jet recording method of so-called bubble jet type is known in which an instantaneous state change resulting in an instantaneous volume change (bubble generation) is caused by application of energy such as heat to the ink, so as to eject the ink through the ejection outlet by the force resulted from the state change by which the ink is ejected to and deposited on the recording material to form an image formation. As disclosed in U.S. Pat. No. 4,723,129 and so on, a recording device using the bubble jet recording method comprises an ejection outlet for ejecting the ink, an ink flow path in fluid communication with the ejection outlet, and an electrothermal transducer as energy generating means disposed in the ink flow path. With such a recording method is advantageous in that, a high quality image, can be recorded at high speed and with low noise, and a plurality of such ejection outlets can be posited at high density, and therefore, small size recording apparatus capable of providing a high resolution can be provided, and color images can be easily formed. Therefore, the bubble jet recording method is now widely used in printers, copying machines, facsimile machines or another office equipment, and for industrial systems such as textile printing device or the like.
With the increase of the wide needs for the bubble jet technique, various demands are imposed thereon, recently.
For example, an improvement in energy use efficiency is demanded. To meed the demand, the optimization of the heat generating element such as adjustment of the thickness of the protecting film is investigated. This method is effective in that propagation efficiency of the generated heat to the liquid is improved.
In order to provide high quality images, driving conditions have been proposed by which the ink ejection speed is increased, and/or the bubble generation is stabilized to accomplish better ink ejection. As another example, from the standpoint of increasing the recording speed, flow passage configuration improvements have been proposed by which the speed of liquid filling (refilling) into the liquid flow path is increased.
Japanese Laid Open Patent Application No. SHO-63-199972 and so on discloses a flow passage structure. The backward wave is known as an energy loss since it is not directed toward the ejecting direction.
Japanese Laid Open Patent Application No. SHO-63-199972 disclose a valve 10 spaced from a generating region of the bubble generated by the heat generating element 2 in a direction away from the ejection outlet 11. The valve 4 has an initial position where it is stuck on the ceiling of the flow path 5, and suspends into the flow path 5 upon the generation of the bubble. The loss is said to be suppressed by controlling a part of the backward wave by the valve 4.
On the other hand, in the bubble jet recording method, the heating is repeated with the heat generating element contacted with the ink, and therefore, a burnt material is deposited on the surface of the heat generating element due to burnt deposit of the ink. However, the amount of the deposition may be large depending on the materials of the ink. If this occurs, the ink ejection becomes unstable. Additionally, even when the liquid to be ejected is the one easily deteriorated by heat or even when the liquid is the one with which the bubble generated is not sufficient, the liquid is desired to be ejected in good order without property change.
From this standpoint, Japanese Laid Open Patent Application No. SHO-61-69467, Japanese Laid Open Patent Application No. SHO-55-81172 and U.S. Pat. No. 4,480,259 disclose that different liquids are used for the liquid generating the bubble by the heat (bubble generating liquid) and for the liquid to be ejected (ejection liquid). In these publications, the ink as the ejection liquid and the bubble generation liquid are completely separated by a flexible film of silicone rubber or the like so as to prevent direct contact of the ejection liquid to the heat generating element while propagating the pressure resulting from the bubble generation of the bubble generation liquid to the ejection liquid by the deformation of the flexible film. The prevention of the deposition of the material on the surface of the heat generating element and the increase of the selection latitude of the ejection liquid are accomplished, by such a structure.
However, in the head wherein the ejection liquid and the bubble generation liquid are completely separated, the pressure upon the bubble generation is propagated to the ejection liquid through the deformation of the flexible film, and therefore, the pressure is absorbed by the flexible film to a quite high extend. In addition, the deformation of the flexible film is not so large, and therefore, the energy use efficiency and the ejection force are deteriorated although the some effect is provided by the provision between the ejection liquid and the bubble generation liquid.
Accordingly, it is a principal object of the present invention to provide liquid ejecting method, head, cartridge and apparatus, wherein the ejection efficiency is stabilized and/or improved.
It is another object of the present invention to provide liquid ejecting method, head, cartridge and apparatus, wherein behavior of a bubble generated in a bubble generating region is controlled.
It is a further object of the present invention to provide liquid ejecting method, head, cartridge and apparatus, wherein factors relating to a liquid flow path, heat generating element, movable member and/or liquid, are properly determined.
According to an aspect of the present invention, the pressure distribution in the flow path or regions, provided by acoustic wave resulting from the generation of the bubble generating region, is effectively used for moving the free end of the movable member. More particularly, the displacing speed of the free end of the movable member higher than the growing speed of the bubble is effective to provide an induction path for the growing bubble. The induction path provides a secondary pressure distribution to properly direct the bubble growth.
According to another aspect of the present invention, a larger volume of the bubble can be used for the ejection.
According to a further aspect of the present invention, a larger component of the bubble is directed toward the ejection outlet. Therefore, the ejection speed and the ejection amount are stabilized in the second period.
According to a further aspect of the present invention, by the area of the heat generating element being 64 to 20000 xcexcm2, the bubble generation is stabilized, and by the area of the movable member and the longitudinal elasticity thereof being 64 to 40000 xcexcm2 and 1xc3x97103 to 1xc3x97106 N/mm2, a height ejection efficiency and durability are provided. By the height of the first liquid flow path being 10-150 xcexcm, the ejection power is stabilized, and by the height of the second liquid flow path being 0.1-40 xcexcm, the ejection efficiency is further enhanced, and the bubble generation is further stabilized. As regards the viscosity of the liquid, when the liquid in the first liquid path is not different from the liquid in the second liquid flow path, is 1 to 100 cp so that ejection is stabilized. When they are separated, the liquid in the first liquid flow path is in the range of 1-1000 cp. By using a liquid ejecting head having the thus limited area of the movable member or the like, the flow of the liquid can be divided by the trace of the free end of the movable member.
In another aspect of the present invention, even if the printing operation is started after the recording head is left in a low temperature or low humidity condition for a long term, the ejection failure can be avoided. Even if the ejection failure occurs, the normal operation is recovered by a small scale recovery process including a preliminary ejection and sucking recovery. According to the present invention, the time required for the recovery can be reduced, and the loss of the liquid by the recovery operation is reduced, so that running cost can be reduced.
In an aspect of improving the refilling property, the responsivity, the stabilized growth of the bubble and stabilization of the liquid droplet during the continuous ejections are accomplished, thus permitting high speed recording.
In this specification, xe2x80x9cupstreamxe2x80x9d and xe2x80x9cdownstreamxe2x80x9d are defined with respect to a general liquid flow from a liquid supply source to the ejection outlet through the bubble generation region (movable member).
As regards the bubble per se, the xe2x80x9cdownstreamxe2x80x9d is defined as toward the ejection outlet side of the bubble which directly function to eject the liquid droplet. More particularly, it generally means a downstream from the center of the bubble with respect to the direction of the general liquid flow, or a downstream from the center of the area of the heat generating element with respect to the same.
In this specification, xe2x80x9csubstantially sealedxe2x80x9d generally means a sealed state in such a degree that when the bubble grows, the bubble does not escape through a gap (slit) around the movable member before motion of the movable member.
In this specification, xe2x80x9cseparation wallxe2x80x9d may mean a wall (which may include the movable member) interposed to separate the region in direct fluid communication with the ejection outlet from the bubble generation region, and more specifically means a wall separating the flow path including the bubble generation region from the liquid flow path in direct fluid communication with the ejection outlet, thus preventing mixture of the liquids in the liquid flow paths.
In this specification, xe2x80x9cgrowing speed of the bubblexe2x80x9d means a maximum speed (m/s) of an interface between the bubble and the liquid which has a component directed toward the movable member.
Additionally, in this specification xe2x80x9csubstantial contact between the bubble and the movable memberxe2x80x9d means a situation under which the bubble and the movable member are physically contacted with each other at least at a part or a situation under which a thin liquid film exists therebetween, and the growth of the bubble and the movement of the movable member are influenced with each other.
These and other objects, features and advantages of the present invention will become more apparent upon a consideration of the following description of the preferred embodiments of the present invention taken in conjunction with the accompanying drawings.